Fix nested value transformation (#49)

Nested values were not being transformed, as `valTransformer` was not
being passed to nested panels.

Let's fix that, and add tests.

Author: Xenonym

src/pair.js

@@ -98,7 +98,10 @@ class ExpandablePair extends Pair {
 
   expand() {
     // Open new panel
-    Panel.renderToEl(this.el, {data: this.val});
+    Panel.renderToEl(this.el, {
+      data: this.val,
+      valTransformer: this.valTransformer
+    });
     this.el.classList.add('expanded');
   }
 

test/jsonpanel.test.js

@@ -98,4 +98,22 @@ describe('value transformer', () => {
       .textContent;
     expect(transformedVal).toBe(`"${testStr.toLowerCase()}"`);
   });
+
+  test('transforms nested values', () => {
+    const testStr = 'A mix Of Upper and Lowercase.';
+
+    jsonpanel({
+      data: {
+        nested: {
+          testStr
+        }
+      },
+      valTransformer: str => str.toLowerCase()
+    });
+
+    document.body.querySelector('.expander').click();
+    const transformedVal = document.body.querySelector('.val.string')
+      .textContent;
+    expect(transformedVal).toBe(`"${testStr.toLowerCase()}"`);
+  });
 });